1. Field of the Invention
The present invention relates to a dental bonding composition and, in particular, to an one-bottle dental bonding composition which is applied onto tooth without any pretreatment of the surface thereof in advance and still provides an excellent bonding layer in a single step, and/or which releases fluoride ion gradually into the oral cavity over an extended period of time.
2. Description of the Related Art
Commercially available dental bonding agents are mainly classified into two groups, a self-etching type and a wet-bonding type as they are called. In the case of bonding agents in the wet-bonding type, the surface of a tooth is treated or etched beforehand with phosphoric acid in order to raise the bonding strength between the tooth and the object to be bonded, and then, while still wet with water after water cleansing, applied with the bonding agent. Such a procedure makes the bonding agent penetrate into tooth deeply in a manner like natural collagen and provides a thicker resin-containing layer on the tooth surface at the same time.
On the other hand, in the case of the bonding agents in the self-etching type, the tooth surface is thoroughly dried by application of blowing air by an air syringe, and subjected, without any pretreatment as described above, to application of a (weakly acidic) bonding agent having a function as an etching agent, thereby providing an bonding layer on the surface of the tooth. By the use of these self-etching bonding agents, the pretreatment process with phosphoric acid inevitably associated with the wet-bonding agents becomes no more required, reducing the risk of the tooth being excessively etched into by phosphoric acid.
However, these methods described in the prior art have disadvantages in that there were required at least two steps to provide the solid bonding layer connecting the tooth and an object to be bonded, thus reducing the efficiency of the manipulation, and that, especially when the bonding agent consists of two or more separately bottled ingredients, addition of another step for mixing and stirring is inevitable, resulting in a possibly large variation in bonding strength of the resulting bonding layer depending on the skill of the practitioners.